Mrs Livni, who now leads the Israeli opposition, is the second prominent Israeli in just over two months to abandon trips to London amid a growing campaign across Europe to press charges against officials involved in military action in Gaza.

Israel’s best-known female politician had been expected to attend a Jewish conference in north London at the weekend before holding private talks with Gordon Brown.

Dozens of protestors massed outside the conference building in Hendon to denounce Mrs Livni. But the opposition leader never arrived after her travel plans were quietly shelved.

Mrs Livni’s aides only added to the growing intrigue surrounding her aborted travel plans on Monday when they insisted her visit had been postponed due to scheduling problems.

The Israeli embassy in London denied any knowledge of an arrest warrant. But human rights lawyers involved in previous action against Israeli officials were more coy, refusing to confirm or deny that they were seeking Mrs Livni’s arrest.

Tayab Ali, a partner at Irvine Thanvi Natas, a London solicitors, said : "We do not comment on individual cases and have nothing to say about news reports of Israeli suspects who cancel arrangements to come to the UK, which is a matter for them."

The Foreign Office expressed its concern over the reports last night and said it would seek to resolve the issue. “The UK is determined to do all it can to promote peace in the Middle East, and to be a strategic partner of Israel,” a spokesman said.

“To do this, Israel’s leaders need to be able to come to the UK for talks with the British Government. We are looking urgently at the implications of this case.”

The controversy comes two months after Moshe Ya’alon, Israel’s vice prime minister, turned down an invitation to visit London on the advice of legal experts in his government. They warned him he could face arrest over an Israeli bombing raid that killed 15 people in Gaza in 2002, when was chief of staff of the Israeli military.

In September, British lawyers for 16 Palestinians petitioned a court to order the arrest of Ehud Barak in connection with January’s war in Gaza while the Israeli defence minister was in London. The court ruled that Mr Barak had diplomatic immunity.

Pro-Palestinian activists have accused Mrs Livni of war crimes and crimes against humanity for her alleged role during Israel’s military operation in Gaza. According to B’Tselem, an Israeli human rights agency, 773 Palestinian civilians were killed during the assault, known as Operation Cast Lead, a figure disputed by the Israeli government.

Mrs Livni, who leads the Kadima party that was founded by Ariel Sharon, has continually defended her actions.

"The opposition chairwoman is proud of all her decisions regarding Operation Cast Lead," her office was quoted as saying. "The operation achieved its objectives to protect the citizens of Israel and to reinstate Israel’s deterrence capability."